Self-Reported Mammogram Use Declines Significantly

ATLANTA, Jan. 25 -- The self-reported use of annual or biennial mammography screening by U.S. women declined by nearly 2% in the years from 2000 to 2005, according to CDC investigators.

The significant decline followed a sharp rise in the 1990s. The new data put the percentage of women 40 and older who said they were screened every year or two at 74.6% (95% confidence interval, 73.8-75.4), down from a high of 76.4% (CI 95%, 75.8-76.9) in 2000 (test for trend, P<0.001), reported A. Blythe Ryerson, M.P.H., and colleagues, in the Jan. 26 issue of Morbidity and Mortality Weekly Report.

"The reason for the apparent decline in screening mammography is unclear and might be attributable to a combination of factors," the CDC group wrote.

"One study has indicated that breast-imaging facilities face challenges such as shortages of key personnel, malpractice concerns, and financial constraints," they continued. "Because the number of U.S. women ages 40 and older years increased by more than 24 million during 1990 to 2000, the number of available facilities and trained breast specialists might not be sufficient to meet the needs of the population, whose overall median age continues to increase."

Other possibilities for the apparent decline in the use of mammography screening, they said, include lack of access to primary care, no insurance, or recent immigration status, the report's authors noted.

The decline "suggests a need to monitor mammography screening more carefully," the MMWR editors commented. "Because mammography screening every one to two years can significantly reduce mortality from breast cancer, continued declines in mammography use might result in increased breast cancer mortality rates."

Breast cancer is the most commonly diagnosed cancer among women in the United States, and is second only to lung and bronchial cancers as a leading cause of cancer-related deaths.

More than 182,000 women in the United States were diagnosed with invasive breast cancer in 2002, and 41,514 died from it.

"Screening mammography can reduce mortality from breast cancer by approximately 20% to 35% in women ages 50 to 69 years and approximately 20% in women ages 40 to 49 years," the CDC authors said.

The U.S. Preventive Services Task Force, and independent panel organized by the Department of Health and Human Services, recommends that women 40 years of age and older be screened for breast cancer with mammography every one to two years, and professional organizations, including the American Medical Association, American Cancer Society, and American College of Obstetricians and Gynecologists support the use of mammographic screening for women age 40 and up, although they differ on recommendations for re-screening.

The CDC report on mammogram screening follows a pattern first detected in results of a recent cohort study of health maintenance organization members. It revealed declining screening rates during 1999-2002.

The current MMWR report, which looked at data from the Behavioral Risk Factor Surveillance System (BRFSS), found a similar trend through 2005, the authors noted.

The surveillance system is a state-based random-digit-dialed telephone survey of the civilian, non-institutionalized adult population in all 50 states, the District of Columbia, Guam, Puerto Rico, and the U.S. Virgin Islands.

From 2000 to 2005, adult women were asked whether they had ever had a mammogram, and respondents who answered yes were then asked how long it had been since their last mammogram.

About half of all women in states and territories who were asked the question responded. The investigators calculated the percentage of all women ages 40 and older who reported having had a mammogram within the past two years, and the estimates were age-adjusted to the 2000 U.S. Census. The authors used logistic regression to assess the linear time trend.

"Since 1999, U.S. women overall ages 40 and older have met the Healthy People 2010 objective of 70% of women having received a mammogram in the preceding two years (objective 3-13)," the MMWR editors commented.

Several limitations of the study pointed out by the editors include:

• The results might overestimate actual breast cancer screening rates because BRFSS does not indicate the reason for the test; certain mammograms might have been used to assess specific breast symptoms or follow-up after an abnormal finding during a clinical breast examination, rather than for routine screening.
• Because the survey is administered by telephone, only women in households with landline telephones are represented; therefore, the results might not be representative of all women.
• Responses are self-reported and not confirmed by review of medical records.
• The survey response rate was low.